Liquid metal micro-switches (LIMMS) have been developed to provide reliable switching capability using compact hardware (e.g., on the order of microns). The small size of LIMMS makes them ideal for use in hybrid circuits and other applications where smaller sizes are desirable. Besides their smaller size, advantages of LIMMS over more conventional switching technologies include reliability, the elimination of mechanical fatigue, lower contact resistance, and the ability to switch relatively high power (e.g., about 100 milli-Watts) without overheating, to name just a few.
According to one design, LIMMS have a main channel partially filled with a liquid metal. The liquid metal may serve as the conductive switching element. Drive elements provided adjacent the main channel move the liquid metal through the main channel, actuating the switching function.
During assembly, the volume of liquid metal must be accurately measured and delivered into the main channel. Failure to accurately measure and/or deliver the proper volume of liquid metal into the main channel could cause the LIMM to fail or malfunction. For example, too much liquid metal in the main channel could cause a short. Not enough liquid metal in the main channel may prevent the switch from making a good connection.
The compact size of LIMMS makes it especially difficult to accurately measure and deliver the liquid metal into the main channel. Even variations in the tolerance of the machinery used to deliver the liquid metal may introduce error during the delivery process. Variations in the dimensions of the main channel itself may also introduce volumetric error.
An embodiment of the invention is a volume adjustment apparatus for a switch. The volume adjustment apparatus may comprise a plate member sized to fit over a main channel in the switch. The plate member displaces an excess of a liquid switching element from the main channel of the switch. At least one collection chamber formed in the plate member overlapping the main channel of the switch receives the displaced excess liquid switching element.
Another embodiment of the invention is a method for adjusting the volume of a liquid switching element in a switch, comprising: depositing the liquid switching element on a substrate; moving a plate member toward the substrate, wherein an excess portion of the liquid switching element moves into at least one collection chamber in the plate member; and removing the plate member with the excess portion of liquid switching element from the substrate.
Yet other embodiments are also disclosed.